A Transformer model may contain stacks of multiple encoder and decoder blocks depending on the problem being solved, as shown in Figure REF  [1]}. The stacked encoder/decoder blocks are similar to multiple hidden layers used in traditional neural networks. However, it is important to note that generally, there is no reduction in the representation dimensions after processing by the encoder or the decoder. The input to the first encoder block is the word sequence mapped into word embeddings with PEs added.
